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Version: 2.0

Data - Data Models

Introduction​

Data Models are a way to represent business objects into an application.

A Data Model is composed of Data Types and relationships between them. Properties can be added to these models and they can be connected together in order to create relations:

new_business_model

Properties and Relations​

Properties are the attributes that have the same lifecycle as the object: when the object is deleted, the property is deleted.

new_property

Relations are the attributes that have a different lifecycle as the object: when the object is deleted, the related object is not deleted. Moreover, it is possible to link more than one object within a single relation: new_relation

Best practices​

Use Strong Typing when defining a Data Model. E.g. : A model which has a temperature property should have a property of type “Temperature” (≠Number). Temperature can then be used independently of the unit (celsius, fahrenheit, …).

Define then functions to get the value as a number: E.g Temperature as °F, Temperature as °C, ...

Exercise 7 – Notes data model​

The goal of this exercise is to create the data model of the "Notes" app. exercise_7_result

  1. Go to Project “Notes”.
  2. Open Folder “Data”.
  3. Create a new Data Model named “Notes Data Model”.
  4. Open the new Data Model.
  5. Create a Data Type named “Note”:
    • Add String property “Summary”
    • Add String property “Content”
  6. Create a Data Type named “Category”:
    • Add String property “Name”
  7. Create a relation from Data Type “Note” to Data Type “Category” by dragging&dropping the "Category" model from the Marketplace to the "Note" Relations field. Name it ”Category”.